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Prediction of shear-related defect locations in semi-solid casting using numerical flow models

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中国有色金属学会会刊：英文版 2010年第S3期20卷 878-882页

作者： F.PINEAU g.d'AMOURS National Research Council of Canada Aluminum Technology Centre501 University BlvdSague nayQcG7H 8C3Canada

Contaminated surfaces of the feedstock materials in aluminum alloy casting processes often produce various types of defects which can affect the tensile properties of the final products as well as their fatigue ***-solid processing takes advantage of a much higher apparent viscosity of the die cast materials by limiting the risk of oxides formed at the free surfaces to become incorporated into the casting when the material is injected into the *** of existing semi-solid processes that use billets as feedstock material are however tied up with a different type of contaminated *** the injection phase,the external-skin on the periphery of the billet,which has been in contact with air and lubricant during the transfer in the shot sleeve,can be incorporated into the *** subjected to a heat treatment,the lubricant is decomposed and produces lens shape *** might be a cause of reject for most structural *** avoid this kind of defects,the paths along which the billet skin evolves must be controlled during *** order to investigate the possibility of skin inclusion into cast parts during injection of the billet,a two-phase finite element mixture model is employed to model the metal *** formation of a skin on the periphery of the billet is modeled by setting an initial solid phase concentration profile in the radial *** observations of the real castings show that the approach is able to model the shear layers and to predict the paths along which the"lens porosity"defects could be *** Arbitrary Eulerian-Lagangian(ALE) method is also investigated and appears to be very promising to follow the skin movement in the casting.

关键词： oxide skin defects two-phase flow finite element modeling Arbitrary Eulerian-Lagangian(ALE) method

An investigation of roof runoff during rain events at the Royal Military College of Canada and potential discharge to Lake Ontario

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Journal of Environmental Sciences 2011年第7期23卷 1072-1078页

作者： david g. Kelly Ron d. Weir Steven d. White Analytical Sciences group & SLOWPOKE-2 Facility at RMC Department of Chemistry and Chemical Engineering Royal Military College of Canada 11 General Crerar Crescent

The Royal Military College of Canada, located on the north eastern shore of Lake Ontario, possesses an abundance of copper roofs and lacks surface water treatment prior to discharge into Lake Ontario. Rainwater, roof runoff and soil samples were collected and analyzed for copper and other parameters. Copper was consistently detected in runoff samples with average concentrations of 3200 ± 2100 μg/L. Multivariable linear regression analysis for a dependant copper runoff concentration yielded an adjusted R 2 value of 0.611, based on an independent variable model using minimum temperature, maximum temperature, total precipitation, and wind speed. Lake water samples taken in the vicinity of storm water outfalls draining areas with copper roofs ranged from 2.0 to 40 μg/L copper. Such data exceed the 2.0 μg/L Canadian Water Quality guidelines for the Protection of Aquatic Life as outlined by the Canadian Council of Ministers of the Environment （CCME）. Analysis of raw, filtered and digested forms suggested that the majority of copper present in runoff and lake water samples was in a dissolved form. The majority of soils taken in this study displayed copper concentrations below the 63 μg/g CCME residential/parkland land use limits. These findings suggested that ion exchange processes between runoff water and soil do not occur to a sufficient extent to elevate copper levels in soil. It may therefore be concluded that the eventual fate of copper, which is not discharged via storm water outfalls, is lost to the water table and Lake Ontario through the sub-soil.

关键词： copper roof runoff Lake Ontario Canadian water quality guidelines for the protection of aquatic life

NUMERICAL SOLUTIONS OF INCOMPRESSIBLE EULER ANd NAVIER-STOKES EQUATIONS BY EFFICIENT dISCRETE SINgULAR CONVOLUTION METHOd

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Acta Mechanica Sinica 2000年第3期16卷 223-239页

作者： d.C.Wan g.W.Wei Shanghai Univ Shanghai Inst Appl Math&MechShanghai 200072Peoples R China Natl Univ Singapore Dept Computat SciSingapore 119260Singapore

An efficient discrete singular convolution (dSC) method is introduced to the numerical solutions of incompressible Euler and Navier-Stokes equations with periodic boundary conditions. Two numerical tests of two-dimensional Navier-Stokes equations with periodic boundary conditions and Euler equations for doubly periodic shear layer flows are carried out by using the dSC method for spatial derivatives and fourth-order Runge-Kutta method for time advancement, respectively. The computational results show that the dSC method is efficient and robust for solving tho problems of incompressible flows, and has the potential of being extended to numerically solve much broader problems in fluid dynamics.

关键词： incompressible flows periodic boundary dSC method fourth-order Runge-Kutta method

Solid state interfacial reactions in electrodeposited Cu/Sn couples

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中国有色金属学会会刊：英文版 2010年第1期20卷 90-96页

作者：汤文明 d. g. IVEY School of Materials Science and Engineering Hefei University of Technology department of Chemical and Materials Engineering University of Alberta Edmonton Alberta T6G 2G6 Canada

Cu/Sn couples, prepared by sequentially electroplating Cu and Sn layers on metallized Si wafers, were employed to study the microstructures, phases and the growth kinetics of Cu-Sn intermediate phases, when electroplated Cu/Sn couples were aged at room temperature or annealed at temperatures from 373 K to 498 K for various time. Only Cu6Sn5 formed in aged couples or couples annealed at temperature below 398 K. The Cu6Sn5 layer was continuous, but not uniform, with protrusions extending into the Sn matrix. When Cu/Sn couples were annealed at temperatures from 423 K to 498 K, two continuous and uniform Cn6Sn5/Cu3Sn layers formed within the reaction region between Sn and Cu. There were many voids near the Cu3Sn/Cu interface and within the Cu3Sn layer. Cu6Sn5 and Cu3Sn formations both follow parabolic growth kinetics with activation energies of 41.4 kJ/mol for Cu6Sn5 and 90.4 kJ/mol for Cu3Sn, respectively.

关键词：电镀铜固态反应锡退火温度生长动力学种族金属硅微结构

Synthesis of layered LiMnO_2 by in situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

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Chinese Science Bulletin 2005年第3期50卷 213-216页

作者： d.g.Evans Key Laboratory of Science and Technology of Controllable Chemical Reactions Ministry of EducationBeijing University of Chemical Tech- nologyBeijing 100029China

Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2S2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was characterized by XRd, ICP, TEM and Li-NMR. The results reveal that 7 orthorhombic LiMnO2 with high purity and good crystallin- ity can be obtained by this method. during electrochemical tests, a LiMnO2/Li cell shows an initial reversible capacity of 208 mAh·g?1 and a reversible capacity of 180 mAh·g?1 after 30 cycles at room temperature.

关键词： LiMnO2 氧化反应电化学特性锂离子电池分析方法

Applications and verification of a computational energy dynamics model for mine climate simulations

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International Journal of Mining Science and Technology 2020年第4期30卷 483-493页

作者： g.danko d.Bahrami C.Stewart department of Mining and Metallurgical Engineering University of NevadaRenoNV 89557USA School of Mechanical Engineering University of QueenslandQueensland 4072Australia

A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground *** method is called the Computational Energy dynamics(CEd)model of the heat,mass,and energy *** Thermal and Humidity(TH)transport elements of the full model are described for advection,convection,and accumulation,encompassing heat capacity,radiation,latent heat for evaporation,and condensation in the airways,as well as variable heat conduction and accumulation in the rock *** thermal flywheel effect for time-dependent temperature field applications is included in the model solution.A CEd model validation exercise is described,directly evaluating the iterated,minimized energy balance errors for the mechanical and thermal energy components for each network branch after a converged solution is determined.A simulation example relevant to mine safety and health is shown with the CEd-TH model,demonstrating its capabilities in efficiency and accuracy in comparison with measurement results.

关键词： Mine climate simulation dynamic heat flow model Coupled heat and moisture transport Computational energy dynamics Mine safety and health

MECHANICAL STABILIZATION OF dEFORMEd AUSTENITEdURINg CONTINUOUS COOLINg TRANSFORMATION IN AC-Mn-Cr-Ni-Mo PLASTIC dIE STEEL

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 93-99页

作者： d.S.Liu g.d.Wang X.H.Liu g.Z.Cui Northeastern Univ Shenyang China

The influence of prior austenite deformed at different temperature on the subsequent continuous cooling bainitic transformation has been investigated in an C-Ma-Cr-Ni-Mo plastic die steel. The results show that the prior deformation in low temperature region of austenite retards significantly the bainitic transformation. For the same continuous cooling schedule, as austenite deformed at lower temperature, the quantity of the classical sheaf-like bainite becomes less. The present results show that severe deformation leads to mechanical stabilization of austenite and causes the difficulty of bainitic ferrite propagation into the austenite.

关键词： plastic die steel deformed austenite continuous cooling bainitic transformation mechanical stabilization of austenite

Implications of crude oil pollution on natural regeneration of plant species in an oil-producing community in the Niger delta Region of Nigeria

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Journal of Forestry Research 2014年第4期25卷 915-921页

作者： U.d Chima g.Vure department of Forestry and Wildlife Management University of Port Harcourt- Choba P.M.B. 5323 Port Harcourt Rivers State Nigeria

The study evaluated the impact of crude oil pollution on natu- ral regeneration of plant species in a major oil-producing community in the Niger delta region of Nigeria. Three sites--unpolluted site （US）, polluted and untreated site （PUS）, and polluted and treated site （PTS）-- were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0-10 cm and 10--20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0-10 em US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0-10/10-20 cm of the PTS respectively. At 10-20 cm, non-woody species of theUS were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0-10/10-20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10-20 cm than 0-10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively af- fected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.

关键词： Ogoni land crude oil pollution remediation plant regeneration

Structure of Interphase Boundaries in Bimetallic Thin Films

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Journal of Materials Science & Technology 2001年第1期17卷 59-60页

作者： M.d.Starostenkov g.M.Poletayev d.M.Starostenkov general Physics department Altai State Technical UniversityBarnaulRussia

The structural transformation in thin films of bimetals in the dependence on temperature and concentration of vacancies was investigated. The system Ni-Al structural transformation was realized by computer design according to the mechanism of self-sustained high(temperature synthesis. Structural transformation is characterized by the presence of dislocations, clusters of point defects and germs of intermetallic phases near interphase boundaries.

关键词： structural transformation intermetallic phases thin films